“It is not necessarily a fact that someone who is academically smart makes a better teacher than someone who isn’t,” Mr Garrett told reporters in Canberra.

“I don’t think education should necessarily be the province of the particularly smart or gifted.”

New South Wales plans to raise professional standards and make it easier to fire underperforming teachers. NSW Education Minister Adrian Piccoli said university entrance scores for people studying teaching were sometimes too low. He wants teacher training schools to “limit training places as a way of combating the national oversupply of new teachers due partly to the federal government’s decision to deregulate university places.”

. . . their principals and district officials treated them basically the same. Two-thirds of the districts’ best teachers weren’t even encouraged to return another year.

Three-quarters of low-performing teachers told TNTP that they plan to stay at the current school; half said they intend to teach for another decade. The average brand-new teacher would be more effective than these low performers, the report concludes.

Even without merit pay, districts could do much more to retain the best teachers, the report adds.

If principals simply gave their best teachers regular feedback, identified leadership opportunities for them, publicly recognized their accomplishments, and employed other, basic HR tactics, they could significantly reduce the attrition rate.

“The nation’s 50 largest districts lose approximately 10,000 Irreplaceables each year, according to TNTP. Yet the culture of teaching insists that all teachers are the same.

New York City’s master teacher program paid Lori Wheal more “in exchange for spending extra time mentoring my peers, writing curricula and running professional development.” She felt her work was respected. When her middle school lost the funding, she quit teaching, she writes in the New York Post.

. . . the city needs to hold principals accountable for fixing school cultures that drive top teachers away. This means improving working conditions and creating environments of mutual respect and trust. (And give principals credit on their own performance reviews for retaining great teachers.)

But it also means refusing to turn a blind eye to poor teaching. Struggling teachers deserve support and a reasonable chance to improve. But if they can’t, they shouldn’t stay in the classroom.

. . . since the mid-1950s, the U.S. student population has increased by 60 percent, while the number of public education workers, including teachers, administrators, and other non-certificated staff, has exploded by 300 percent.

. . . What’s more, according to the National Center for Education Statistics, teacher-pupil ratios across the nation have diminished steadily since 1955, when the ratio of public school teachers to students was 26.9 to one. By 1970, the ratio was 22.3 to one. And by 2007, the last year for which federal government statistics are available, the ratio came down to 15.5 to one.

Tennessee’s STAR experiment found lasting benefits, especially for black students, for classes of 14 to 17 students in kindergarten through third grade. Most of the gains appear to have occurred in kindergarten and first grade.

Other studies have found no achievement gains in smaller classes, Sand writes.

When California paid schools to cut K-3 classes to 20 students, suburban districts were able to hire good teachers to teach the additional classes. Inner-city schools made do with anyone they could find. As a result, a RAND analysis found class-size reduction had no benefit for urban students.

If districts fired the lowest-performing 5 percent of teachers without hiring replacements, class sizes would rise only slightly, Sand writes. The savings could be used for “increased salaries, books, computers, or whatever the individual school district chooses.”